// Tencent is pleased to support the open source community by making RapidJSON available.
// 
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// http://opensource.org/licenses/MIT
//
// Unless required by applicable law or agreed to in writing, software distributed 
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
// CONDITIONS OF ANY KIND, either express or implied. See the License for the 
// specific language governing permissions and limitations under the License.

#ifndef RAPIDJSON_ISTREAMWRAPPER_H_
#define RAPIDJSON_ISTREAMWRAPPER_H_

#include "stream.h"
#include <iosfwd>

#ifdef __clang__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(padded)
#endif

#ifdef _MSC_VER
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(4351) // new behavior: elements of array 'array' will be default initialized
#endif

RAPIDJSON_NAMESPACE_BEGIN

//! Wrapper of \c std::basic_istream into RapidJSON's Stream concept.
/*!
    The classes can be wrapped including but not limited to:

    - \c std::istringstream
    - \c std::stringstream
    - \c std::wistringstream
    - \c std::wstringstream
    - \c std::ifstream
    - \c std::fstream
    - \c std::wifstream
    - \c std::wfstream

    \tparam StreamType Class derived from \c std::basic_istream.
*/

    template<typename StreamType>
    class BasicIStreamWrapper {
    public:
        typedef typename StreamType::char_type Ch;

        BasicIStreamWrapper(StreamType &stream) : stream_(stream), count_(), peekBuffer_() {}

        Ch Peek() const {
            typename StreamType::int_type c = stream_.peek();
            return RAPIDJSON_LIKELY(c != StreamType::traits_type::eof()) ? static_cast<Ch>(c) : '\0';
        }

        Ch Take() {
            typename StreamType::int_type c = stream_.get();
            if (RAPIDJSON_LIKELY(c != StreamType::traits_type::eof())) {
                count_++;
                return static_cast<Ch>(c);
            } else
                return '\0';
        }

        // tellg() may return -1 when failed. So we count by ourself.
        size_t Tell() const { return count_; }

        Ch *PutBegin() {
            RAPIDJSON_ASSERT(false);
            return 0;
        }

        void Put(Ch) { RAPIDJSON_ASSERT(false); }

        void Flush() { RAPIDJSON_ASSERT(false); }

        size_t PutEnd(Ch *) {
            RAPIDJSON_ASSERT(false);
            return 0;
        }

        // For encoding detection only.
        const Ch *Peek4() const {
            RAPIDJSON_ASSERT(sizeof(Ch) == 1); // Only usable for byte stream.
            int i;
            bool hasError = false;
            for (i = 0; i < 4; ++i) {
                typename StreamType::int_type c = stream_.get();
                if (c == StreamType::traits_type::eof()) {
                    hasError = true;
                    stream_.clear();
                    break;
                }
                peekBuffer_[i] = static_cast<Ch>(c);
            }
            for (--i; i >= 0; --i)
                stream_.putback(peekBuffer_[i]);
            return !hasError ? peekBuffer_ : 0;
        }

    private:
        BasicIStreamWrapper(const BasicIStreamWrapper &);

        BasicIStreamWrapper &operator=(const BasicIStreamWrapper &);

        StreamType &stream_;
        size_t count_;  //!< Number of characters read. Note:
        mutable Ch peekBuffer_[4];
    };

    typedef BasicIStreamWrapper<std::istream> IStreamWrapper;
    typedef BasicIStreamWrapper<std::wistream> WIStreamWrapper;

#if defined(__clang__) || defined(_MSC_VER)
    RAPIDJSON_DIAG_POP
#endif

RAPIDJSON_NAMESPACE_END

#endif // RAPIDJSON_ISTREAMWRAPPER_H_
